Synthesis, crystal structures and IR spectra of isotypic pseudopolymorphs complexes of Zn(II) by indole-2-carboxylic acid and 2,9-dimethyl-1,10-phenanthroline with different solvates (DMA, DMF or DMSO)

Three ternary complexes of zinc indole-2-carboxylate (2-IC) with 2,9-dimethyl-1,10-phenanthroline (NC) in dimethylacetamide (DMA), dimethylformamide (DMF) or dimethyl sulfoxide (DMSO) were synthesized, their X-ray crystal structure and IR spectra were determined. In compound [Zn(2-IC)2(NC)]$(DMA) (1), Zn is five-coordinate by one bidentate NC ligand and two 2-IC anionic ligands one of which is monodentate, and the other is bidentate. The individual molecules are linked into chains running parallel to the a-axis by intermolecular hydrogen bonding.The crystal structure is completed by aDMAsolvatemolecule.Compounds [Zn(2-IC)2(NC)]$(DMF) (2) and [Zn(2-IC)2(NC)]$(DMSO) (3) contain onemonomeric zinc complex similar to 1 and a disordered solvatemolecule (DMF in 2;DMSOin3) incontrast to1. In the IR spectra of the three compounds, themost important feature is the appearance of a very broad band at about 3175 cmK1 presenting a fine structure which can be correlated to hydrogen bonds in N–H/O bifurcated links, via inter and intramolecular interactions. A tentative assignment was made to point out the bidentate or monodentate carboxylate groups attached to the Zn atom. q 2005 Elsevier B.V. All rights reserved